The wheels of history have a tendency to roll back over the same ground. For the past 33 years — since, as they see it, the wanton era of the 1960's culminated in the Supreme Court's Roe v. Wade decision in 1973 — American social conservatives have been on an unyielding campaign against abortion. But recently, as the conservative tide has continued to swell, this campaign has taken on a broader scope. Its true beginning point may not be Roe but Griswold v. Connecticut, the 1965 case that had the effect of legalizing contraception. "We see a direct connection between the practice of contraception and the practice of abortion," says Judie Brown, president of the American Life League, an organization that has battled abortion for 27 years but that, like others, now has a larger mission. "The mind-set that invites a couple to use contraception is an antichild mind-set," she told me. "So when a baby is conceived accidentally, the couple already have this negative attitude toward the child. Therefore seeking an abortion is a natural outcome. We oppose all forms of contraception."

The American Life League is a lay Catholic organization, and for years — especially since Pope Paul VI's "Humanae Vitae" encyclical of 1968 forbade "any action which either before, at the moment of or after sexual intercourse, is specifically intended to prevent procreation" — being anti-contraception was largely a Catholic thing. Protestants and other non-Catholics tended to look on curiously as they took part in the general societywide acceptance of various forms of birth control. But no longer. Organizations like the Christian Medical and Dental Associations, which inject a mixture of religion and medicine into the social sphere, operate from a broadly Christian perspective that includes opposition to some forms of birth control. Edward R. Martin Jr., a lawyer for the public-interest law firm Americans United for Life, whose work includes seeking to restrict abortion at the state level and representing pharmacists who have refused to prescribe emergency contraception, told me: "We see contraception and abortion as part of a mind-set that's worrisome in terms of respecting life. If you're trying to build a culture of life, then you have to start from the very beginning of life, from conception, and you have to include how we think and act with regard to sexuality and contraception." Dr. Joseph B. Stanford, who was appointed by President Bush in 2002 to the F.D.A.'s Reproductive Health Drugs Advisory Committee despite (or perhaps because of) his opposition to contraception, sounded not a little like Daniel Defoe in a 1999 essay he wrote: "Sexual union in marriage ought to be a complete giving of each spouse to the other, and when fertility (or potential fertility) is deliberately excluded from that giving I am convinced that something valuable is lost. A husband will sometimes begin to see his wife as an object of sexual pleasure who should always be available for gratification."

As with other efforts — against gay marriage, stem cell research, cloning, assisted suicide — the anti-birth-control campaign isn't centralized; it seems rather to be part of the evolution of the conservative movement. The subject is talked about in evangelical churches and is on the agenda at the major Bible-based conservative organizations like Focus on the Family and the Christian Coalition. It also has its point people in Congress — including Representative Roscoe Bartlett of Maryland, Representative Chris Smith of New Jersey, Representative Joe Pitts and Representative Melissa Hart of Pennsylvania and Senator Tom Coburn of Oklahoma — all Republicans who have led opposition to various forms of contraception.

R. Albert Mohler Jr., president of the Southern Baptist Theological Seminary, is considered one of the leading intellectual figures of evangelical Christianity in the U.S. In a December 2005 column in The Christian Post titled "Can Christians Use Birth Control?" he wrote: "The effective separation of sex from procreation may be one of the most important defining marks of our age — and one of the most ominous. This awareness is spreading among American evangelicals, and it threatens to set loose a firestorm.. . .A growing number of evangelicals are rethinking the issue of birth control — and facing the hard questions posed by reproductive technologies."...

Many Christians who are active in the evolving anti-birth-control arena state frankly that what links their efforts is a religious commitment to altering the moral landscape of the country. In particular, and not to put too fine a point on it, they want to change the way Americans have sex. Dr. Stanford, the F.D.A. adviser on reproductive-health drugs, proclaimed himself "fully committed to promoting an understanding of human sexuality and procreation radically at odds with the prevailing views and practices of our contemporary culture." Focus on the Family posts a kind of contraceptive warning label on its Web site: "Modern contraceptive inventions have given many an exaggerated sense of safety and prompted more people than ever before to move sexual expression outside the marriage boundary." Contraception, by this logic, encourages sexual promiscuity, sexual deviance (like homosexuality) and a preoccupation with sex that is unhealthful even within marriage.

When I mentioned that I was reading this article to my wife, she replied without hesitation: Why don't they just cut their penises off?